Solid state lighting (SSL) apparatus having electrically conductive sheets coupled to solid state lighting on an SSL element carrier

ABSTRACT

A disclosed lighting apparatus includes a light-diffusive plate having opposing first and second faces bounded by one or more sides. A first electrically conductive sheet is disposed on the first face of the light-diffusive plate, and an electrically insulative sheet is disposed on the first electrically conductive sheet. A second electrically conductive sheet is disposed on the electrically insulative sheet. A plurality of solid-state lighting (SSL) elements have light emitting portions that face a portion of the light-diffusive plate. The SSL elements are electrically coupled to the first electrically conductive sheet and to the second electrically conductive sheet.

FIELD OF THE INVENTION

The disclosed embodiments generally relate to a solid-state lighting(SSL) apparatus.

BACKGROUND

Solid-state lighting (SSL) apparatuses have semiconductor structuresthat emit light. Examples of SSL lighting elements includelight-emitting diodes (LEDs), semiconductor laser diodes (LDs), organiclight-emitting diodes (OLED), polymer light-emitting diodes (PLED), orquantum dots. SSL is becoming more popular due in part to the energyefficient qualities and durability of SSL. Applications for SSL mayinclude advertising signage, decorations, or utility and general purposelighting. In some implementations, SSL elements are placed along one ormore edges of a light-transmitting panel, and the light-transmittingpanel is configured to evenly distribute light emitted from the SSLelements through a surface of the panel.

With an edge-lit light-transmitting panel, light from the SSL elementsis spread evenly through the panel by total internal reflection.Disruptions formed on the surface of the panel scatter incident light sothat light is emitted from the surface of the panel.

SUMMARY

One lighting apparatus includes a light-diffusive plate having opposingfirst and second faces bounded by one or more sides. A firstelectrically conductive sheet is disposed on the first face of thelight-diffusive plate, and an electrically insulative sheet is disposedon the first electrically conductive sheet. A second electricallyconductive sheet is disposed on the electrically insulative sheet. Aplurality of solid-state lighting (SSL) elements have light emittingportions that face a portion of the light-diffusive plate. The SSLelements are electrically coupled to the first electrically conductivesheet and to the second electrically conductive sheet.

In another embodiment, a method of making a lighting apparatus includesdisposing a first electrically conductive sheet on a first face of thelight-diffusive plate. The light-diffusive plate has opposing first andsecond faces bounded by one or more sides. A plurality of SSL elementsare connected to the first electrically conductive sheet with theplurality of SSL elements arranged to emit light toward a portion of thelight-diffusive plate. An electrically insulative sheet is disposed onthe first electrically conductive sheet. A second electricallyconductive sheet is disposed on the electrically insulative sheet, andthe SSL elements are connected to the second electrically conductivesheet.

The above summary is not intended to describe each disclosed embodiment.The figures and detailed description that follow provide additionalexample embodiments and aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects and advantages will become apparent upon review of theDetailed Description and upon reference to the drawings in which:

FIG. 1 shows an exploded view of a lighting apparatus;

FIG. 2 shows a partial view of an SSL element carrier;

FIG. 3 shows a partial cross-sectional view of the lighting apparatus ofFIG. 1 taken in the direction of cross-section lines 3;

FIG. 4 shows a partial cross-sectional view of a lighting apparatusaccording to an implementation in which there is no channel in the sideof the light-diffusive plate;

FIG. 5 is a flowchart of a process for constructing a lightingapparatus;

FIG. 6 shows a partial cross-sectional view of a lighting apparatusaccording to a configuration in which there is no channel in the side ofthe light-diffusive plate, and the terminals are disposed on the samesurface of the SSL element carrier, which is illustrated in FIG. 3;

FIG. 7 is a flowchart of a process for constructing a lightingapparatus;

FIG. 8 shows an exploded view of a lighting apparatus according toanother implementation;

FIG. 9 is a side, cross-sectional view of a portion of a back-litlighting apparatus similar to the lighting apparatus of FIG. 8;

FIG. 10 is a side, cross-sectional view of a portion of a back-litlighting apparatus similar to the lighting apparatus of FIG. 8, with anadditional electrically insulative layer and electrically conductivelayer;

FIG. 11 is a side, cross-sectional view of a portion of a back-litlighting apparatus similar to the lighting apparatus of FIG. 8, with anadditional control wire;

FIG. 12 shows an enclosure; and

FIG. 13 shows a heat sink.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth todescribe specific examples presented herein. It should be apparent,however, to one skilled in the art, that one or more other examplesand/or variations of these examples may be practiced without all thespecific details given below. In other instances, well known featureshave not been described in detail so as not to obscure the descriptionof the examples herein. For ease of illustration, the same referencenumerals may be used in different diagrams to refer to the same elementsor additional instances of the same element.

This disclosure describes an SSL apparatus that provides evendistribution of current to the SSL elements and efficient dissipation ofheat from the SSL elements. The SSL apparatus is adaptable for variousapplications, including signage or general lighting.

The lighting apparatus includes a light-diffusive plate that hasdisruptions formed on one of the faces for scattering internallyreflected light. SSL elements are attached to an SSL element carrier,and the SSL element carrier is attached to the light-diffusive platesuch that light emitting portions of the SSL elements face one of thesides that surround the faces of the light-diffusive plate. Powerterminals are disposed on another portion of the SSL element carrier. Afirst electrically conductive sheet is disposed on the light-diffusiveplate on the face having the disruptions. The first electricallyconductive sheet is electrically and mechanically coupled to the firstterminals on the SSL element carrier. An electrically insulative sheetis disposed on the first conductive sheet, and a second electricallyconductive sheet is disposed on the electrically insulative sheet. Thesecond electrically conductive sheet is electrically and mechanicallycoupled to the second terminals on the SSL element carrier.

FIG. 1 shows an exploded view of a lighting apparatus 100 according toone implementation. The lighting apparatus includes a light-diffusiveplate 102, an SSL element carrier 104, first and second electricallyconductive sheets 106 and 108, and an electrically insulative sheet 110disposed between the first and second electrically conductive sheets.The first and second electrically conductive sheets 106 and 108, whichare illustrated with thicker line segments, may be aluminum or copper,depending on implementation requirements. Also, the thickness of theelectrically conductive sheets may vary, such as from foil to thickersheets. The evenness of current distribution and ability to dissipateheat by the electrically conductive sheets may vary according to thesurface area and thickness of the sheets.

The light-diffusive plate 102 has opposing first and second faces 120and 122 that are bounded by one or more sides. In the illustratedexample, the light-diffusive plate is rectangular and has four sides,with sides 112 and 114 exposed and sides 116 and 118 hidden in the view.The first face 120 is mostly obscured by the electrically conductivesheet 106, and the opposing second face 122 is hidden in the view. Thelight-diffusive plate has multiple disruptions (not shown in FIG. 1; seeFIGS. 3 and 4) on the first face. Though not shown in FIG. 1, thelight-diffusive plate has disruptions formed on one face 120 of theopposing faces of the plate. With an edge-lit lighting apparatus, lightfrom the SSL elements is spread evenly through the light-diffusive plateby total internal reflection. The disruptions formed on the surface ofthe plate scatter incident light so that light is emitted from the faceof the plate having the disruptions. Another implementation hasdisruptions formed on both face 120 and the opposing face 122 of thelight-diffusive plate.

In one implementation, the light-diffusive plate is made from atransparent thermoplastic such as polymethyl methacrylate (PMMA or“acrylic glass”). The light-diffusive plate 102 may be any polygon or ashape bounded by one or more curved sides, such as a circle, ellipse, oran irregular shape.

The first electrically conductive sheet 106 is disposed on the firstface 120 of the light-diffusive plate 102 and may be attached to thelight-diffusive plate with adhesive between edge areas of theelectrically conductive sheet and the light-diffusive plate. Inalternative implementations, a frame (not shown) may hold together theelectrically conductive sheets 106 and 108, the insulative sheet 110,the SSL element carrier 104, and the light-diffusive plate.

Multiple SSL elements 124 are attached to a portion 126 of the SSLelement carrier 104, and the SSL element carrier is attached to thelight-diffusive plate 102 such that light-emitting portions of the SSLelements face one of the sides of the light-diffusive plate. In lightingapparatus 100, the SSL elements face side 116 of the light diffusiveplate 102. The SSL elements 124 may be packaged SSL elements or baredice.

On the SSL element carrier 104, the SSL elements 124 are connected torespective terminals that are disposed on a second portion of thecarrier. In an example of an implementation of the SSL element carrier,the second portion of the carrier includes respective tabs for theterminals. For example, tabs 128 and 129 have terminals 130 and 134,respectively. For each SSL element, a respective pair of terminalsincludes one terminal coupled to the anode of the SSL element, andanother terminal coupled to the cathode of the SSL element. For example,terminal 130 is coupled to the anode of SSL element 132, and terminal134 is coupled to the cathode. A current control device, such as aresistor, may be coupled between one of the power terminals and theanode/cathode. For example, current control device 136 is coupledbetween terminal 130 and the SSL element 132. Though not shown, it willbe appreciated that the SSL element carrier 104 may further includeterminals for connecting to control inputs of the SSL elements.

In one implementation, the SSL element carrier may be a flexiblesubstrate, such as a polyimide substrate, and the terminals forconnecting to the anodes and cathodes of the SSL elements may be copperand disposed on opposing surfaces of the portion 128. For example,terminal 130 may be disposed on the surface of portion 128 that ishidden from view (the terminal is represented by the dashed outline),and terminal 134 may be disposed on the surface of the portion 128 thatis exposed in the view and faces the electrically insulative layer 110and electrically conductive sheet 108. Copper traces on or within thesubstrate connect the terminals to the SSL elements. In anotherimplementation, the SSL element carrier may be a lead frame or a rigidsubstrate.

The SSL element carrier 104 is attached to the light-diffusive plate 102such that the positive terminals (the terminals that are connected tothe anodes of the SSL elements, e.g., terminal 130) face the firstelectrically conductive sheet 106. The first electrically conductivesheet 106 is disposed between the face 120 of the light-diffusive plateand the positive terminals, thereby permitting mechanical and electricalconnections to be established between the terminals and the sheet 106.

The electrically insulative sheet 110 is disposed on the firstelectrically conductive sheet 106 and insulates the first electricallyconductive sheet from the second electrically conductive sheet 108.Adhesive may be used to attach the electrically insulative sheet to thefirst electrically conductive sheet, and the second electricallyconductive sheet to the electrically insulative sheet. A portion 142 ofthe second electrically conductive sheet extends beyond the insulativesheet and contacts the negative terminals (the terminals that areconnected to the cathodes of the SSL elements, e.g., terminal 134) onthe SSL element carrier 104, thereby permitting mechanical andelectrical connections to be established between the terminals and thesecond electrically conductive sheet. The electrically conductive sheets106 and 108 may include respective tabs 144 and 146 for connecting to apower source.

In some implementations, the anode terminals (e.g., 130) may beconnected to the first electrically conductive sheet 106 with weldjoints. Similarly, the cathode terminals (e.g., 134) may be connected tothe second electrically conductive sheet 108 with weld joints. Thewelding of dissimilar metals (such as copper terminals and an aluminumsheet) provides strong and durable joints.

The lighting apparatus 100 may have multiple SSL element carriers (notshown) in another implementation. For example, a second SSL elementcarrier (not shown) may be attached to the light-diffusive plate 102,with the SSL elements of the second SSL element carrier facing side 114of the light-diffusive plate. The terminals of the second SSL elementcarrier may be connected to the first and second electrically conductivesheets as described above.

A channel(s) 152 may be formed along the side(s) 116 of thelight-diffusive plate 102 in some implementations. The channel forms arecess large enough to accommodate the SSL elements 124 on the carrier104, with the SSL element carrier disposed over the channel 152 suchthat the SSL elements are within the channel.

The arrangement of SSL elements in the channel may be varied accordingto implementation requirements. For example, different implementationsmay call for different sizes, numbers, and/or spacing of SSL elements.Also, there may be more than one row of SSL elements disposed in thechannel. Another implementation may have more than one channel formed onthe light-diffusive plate. For example, in addition to channel 152,another channel may be formed along side 114, and an SSL element carriermay be disposed over the channel. Other implementations may havemultiple channels on a single side or multiple channels on multiplesides of the light-diffusive plate. Still other implementations may havethe light diffusive plate without a channel and the SSL elements on theSSL element carrier(s) facing one or more of the sides of the lightdiffusive plate.

The lighting apparatus 100 has anodes of the SSL elements connected tothe electrically conductive plate 106 and the cathodes of the SSLelements connected to the electrically conductive plate 108. It will beappreciated that in an alternative implementation, the cathodes of theSSL elements may be connected to the electrically conductive plate 106and the anodes of the SSL elements may be connected to the electricallyconductive plate 108.

FIG. 2 shows a partial view of an SSL element carrier 104, along with anSSL element 202 and power terminals 204 and 206 connected to the SSLelement according to one configuration of the power terminals on thecarrier. The terminals 204 and 206 are disposed on opposing surfaces ofthe carrier. Terminal 204 is disposed on surface 208, and terminal 206is disposed on surface 210. The terminals are coupled to the anode 212and cathode 214 of the SSL element 202 by copper traces 216 and 218.Terminal 204 is coupled to the anode 212 through current control device222. Placement of the terminals on the opposing surfaces of the SSLelement carrier permits the SSL element carrier to be placed over thefirst electrically conductive sheet 106 and the electrically insulativesheet 110 and the second electrically conductive sheet 108 to be placedover the SSL element carrier for establishing connections between theterminals on the SSL element carrier and the electrically conductivesheets. The tabs 232 and 234 may be beneficial in guiding equipment tothe desired sites for physically connecting the terminals to theelectrically conductive sheets.

FIG. 3 shows a partial view of an SSL element carrier 302, along with anSSL element 304 and power terminals 306 and 308 connected to the SSLelement according to another configuration of the power terminals on thecarrier. The terminals 306 and 308 are disposed on the same surface 310of the carrier. The terminals are coupled to the anode 312 and cathode314 of the SSL element 304 by copper traces 316 and 318. Terminal 306 iscoupled to the anode 312 through current control device 136.

Terminal 308 is disposed on tab 322, and terminal 306 is disposed on tab324. Tab 324 may be disposed over the first electrically conductivesheet 106 (FIG. 1) for connecting the terminal 306 to the firstelectrically conductive sheet, and tab 322 may be disposed over thesecond electrically conductive sheet 108 for connecting the terminal 308to the second electrically conductive sheet. The tab configuration ofFIG. 3 is different from the tab configuration of FIG. 2 in that theterminal 308 is on the same surface 310 of the SSL element carrier asterminal 306. In addition tab 322 is longer than tab 324. In thecompleted lighting arrangement, the longer tab 322 wraps around thesides of the electrically insulative sheet 110 (FIG. 1) and the secondelectrically conductive sheet 108 so as to contact the terminal 308 tothe surface of the second electrically conductive sheet opposite theelectrically insulative sheet.

FIG. 4 shows a partial cross-sectional view of the lighting apparatus ofFIG. 1 taken in the direction of cross-section lines 3. Thecross-sectional view shows the electrically conductive sheets 106 and108 connected to the SSL element carrier 104 in an implementation inwhich the light-diffusive plate 102 has a channel 152 that is covered bySSL element carrier 104. SSL element 402 may be mounted on the carrier104 and connected to conductive traces (not shown) that are either onthe surface of the carrier or in a layer of conductive traces in amultilayer arrangement. The terminals 404 and 406 are connected to theanode and cathode of the SSL element 402. Node 408 represents both theanode and cathode in the cross-sectional view, because the cross-sectioncuts across the SSL element between the anode and cathode.

In an example implementation, the channel 152 is filled with anultra-violet (UV) curable encapsulant 410. In one implementation, theencapsulant serves to secure the SSL element carrier 104 to thelight-diffusive plate 102 as well as to seal components from weatherelements for outdoor applications. The encapsulant should be transparentand non-yellowing. In another implementation, a separate weather-tightadhesive may be used to secure the SSL element carrier to thelight-diffusive plate. The encapsulant may be phosphor-filled or includean organic dye to shift the light (e.g., blue light) emitted from theSSL element 402 to a desired color (e.g., white).

For many signage applications, emission of an even level of light fromthe entire surface of the light-diffusive plate may be desirable.Different patterns of disruptions on light-diffusive plates may be usedto different effect. One pattern that has been found to be particularlyuseful is an edge-to-edge pattern of disruptions formed on the surfaceof the plate. Disruptions 448, 450, and 452 are examples of thedisruptions on face 120 of the light-diffusive plate 102. Thedisruptions may be laser etched as is known in the art. For applicationsin which multiple ones of the light-diffusive plates are disposed sideby side, the pitch between the disruptions on two separate plates isequal to the pitch between disruptions on the same plate. In anotherimplementation, disruptions may be formed on face 122 as well as on face120.

In another implementation, a reflector 460, which is illustrated as athick line, may be disposed between the first electrically conductivesheet 106 and the light-diffusive plate 102 in order to reflect lightemitted from the face 120 of the light-diffusive plate. The reflectormay be a coating on the face 120 of the light-diffusive plate, a coatingon the surface 462 of the first electrically conductive sheet 106, or asheet or film disposed between the face 120 of the light-diffusive plateand the surface 462 of the first electrically conductive sheet. Forconfigurations in which the reflector is a sheet or film, the sheet orfilm may be ultrasonically welded to the light-diffusive plate.

FIG. 5 shows a partial cross-sectional view of a lighting apparatusaccording to an implementation in which there is no channel in the sideof the light-diffusive plate 102′. The elements of FIG. 5 are asdescribed in the description of FIG. 4. However, light-diffusive plate102′ does not have the channel 152 of the light-diffusive plate 102.Thus, SSL element 402 faces side 504 of the light-diffusive plate 102′.

FIG. 6 shows a partial cross-sectional view of a lighting apparatusaccording to a configuration in which there is no channel in the side ofthe light-diffusive plate 102′, and the terminals 306 and 308 aredisposed on the same surface of the SSL element carrier 302, which isillustrated in FIG. 3. The elements of FIG. 6 are as described in thedescription of FIG. 4. However, light-diffusive plate 102′ does not havethe channel 152 of the light-diffusive plate 102. Thus, SSL element 402faces side 504 of the light-diffusive plate 102′. Also, the SSL elementcarrier 302 has tabs 322 and 324, which include the terminals 308 and306, respectively, and the terminals are on the same surface of the SSLelement carrier as shown in FIG. 3. Tab 324 is disposed over surface 602of the first electrically conductive sheet 106, providing contactbetween the terminal 306 and the first electrically conductive sheet.Tab 322 wraps around the side 604 of the second electrically conductivesheet 108, placing terminal 308 in contact with surface 606 of thesecond electrically conductive sheet.

FIG. 7 is a flowchart of a process for constructing a lightingapparatus. The process of FIG. 7 may be adapted for either edge-lit orback-lit lighting apparatus. As such, the order of operations and theparticular operations performed may vary according to the type oflighting apparatus. For an edge-lit lighting apparatus, at block 702,disruptions are formed in a light-diffusive plate. The disruptions maybe formed by laser etching a pattern of dots on one of the faces of thelight diffusive plate, for example. Disruptions may be unnecessary for aback-lit lighting apparatus.

Optionally, a channel(s) may be formed along one or more of the sides ofthe light-diffusive plate at block 703. The channel(s) may extend alonga portion(s) of the side(s) and may be formed by mechanical cutting orgrinding or by laser etching.

A first electrically conductive sheet is disposed on the face of thelight-diffusive plate at block 704. The first electrically conductivesheet may be copper or aluminum and may be attached to thelight-diffusive plate with an adhesive or subsequently secured to thelight-diffusive plate along with other elements of the lightingapparatus with a frame.

At block 708, the SSL elements s are connected to the first electricallyconductive sheet. For an edge-lit lighting apparatus, the SSL elementmay be attached to an SSL element carrier and the SSL element carrierattached to the light-diffusive plate. The SSL element carrier may haveSSL elements attached to a first portion of the SSL element carrier andhave first and second terminals coupled to the SSL elements. The SSLelement carrier is attached to the light-diffusive plate such that theSSL elements s emit light toward a first side of the light-diffusiveplate, and the first terminals face the first electrically conductivesheet. For a lighting apparatus having a channel, the SSL elementcarrier is attached to the light-diffusive plate such that the SSLelements on the SSL element carrier are disposed within the channel. Thechannel may be filled with an ultra-violet (UV) curable encapsulant, andthe encapsulant may then be cured. Multiple SSL element carriers may beattached to the light-diffusive plate in some embodiments. The firstterminals of the SSL element carrier are connected to the firstelectrically conductive sheet. The terminals and electrically conductivesheet may be welded or bonded with an electrically conductive adhesive.

For a back-lit lighting apparatus, the first conductive sheet may haveopenings formed therein. The SSL elements may be attached to thelight-diffusive plate by disposing the SSL elements in the opening andconnecting the SSL elements to the first electrically conductive plate.In an example implementation, the SSL elements may be connected to thefirst electrically conductive sheet by wire bonding terminals of the SSLelements to the first electrically conductive sheet. The wire bonds maybe wedge bonds or ball bonds, for example.

At block 710, an electrically insulative sheet is disposed on the firstelectrically conductive sheet. An adhesive may be used to attach theelectrically insulative sheet to the first electrically conductivesheet, or the electrically insulative sheet may be secured to the otherparts of the lighting apparatus with a frame. The electricallyinsulative sheet may cover the first electrically conductive sheet inwhole or in part, but is large enough to insulate the first electricallyconductive sheet from the second electrically conductive sheet. For anedge-lit lighting apparatus, the second terminals on the SSL elementcarrier are not covered by the electrically insulative sheet and remainexposed for subsequent connection to the second electrically conductivesheet. For a back-lit lighting apparatus, the electrically insulativesheet has openings that are aligned with the openings in the firstelectrically conductive sheet, thereby permitting placement of the SSLelements in the openings.

At block 712, a second electrically conductive sheet is disposed on theelectrically insulative sheet. The second electrically conductive sheetmay be copper or aluminum and may be attached to the electricallyinsulative sheet with an adhesive or subsequently secured to thelight-diffusive plate along with other elements of the lightingapparatus with a frame.

The SSL elements are connected to the second electrically conductivesheet at block 714. For an edge-lit lighting apparatus, the secondterminals of the SSL element carrier are connected to the secondelectrically conductive sheet. The terminals and electrically conductivesheet may be welded or bonded with an electrically conductive adhesive.

For a back-lit lighting apparatus, the second electrically conductivesheet has openings formed therein, and the openings in the secondelectrically conductive sheet are aligned with the openings in the firstelectrically conductive sheet and in the electrically insulative sheet.The aligned openings permit the SSL elements to be placed with thelight-emitting portions directed at the face of the light-diffusiveplate and connections to be made between the SSL elements and the firstand second electrically conductive sheets.

The method may further include adding another conductor to the lightingapparatus for providing control signals to the SSL elements. At block716, an insulated control conductor is disposed on the secondelectrically conductive sheet. The insulated control conductor mayinclude another electrically insulative sheet disposed on the secondelectrically conductive sheet and a third electrically conductive sheetdisposed on the additional electrically insulative sheet. Alternatively,the insulated control conductor may be a conductive wire encased in anelectrically insulative jacket and disposed on the second electricallyconductive sheet.

At block 718, control terminals on the SSL elements are connected to thecontrol conductor. For an edge-lit lighting apparatus, the SSL elementcarrier may have third terminals that are coupled to control terminalsof the SSL elements, and the control terminals of the SSL elementcarrier may be connected to the control conductor. The control terminalsof the SSL element carrier and the control conductor may be welded orbonded with an electrically conductive adhesive.

For a back-lit lighting apparatus having a second electricallyinsulative sheet and a third electrically conductive sheet, the secondelectrically insulative sheet and third electrically conductive sheethave openings that are aligned with the openings of the firstelectrically conductive sheet, the first electrically insulative sheet,and the second electrically conductive sheet. Control terminals on theSSL elements may be wire bonded to the third electrically conductivesheet. For a back-lit lighting apparatus having a control wire disposedon the second electrically conductive sheet, control terminals of theSSL elements may be wire bonded to the control wire.

FIG. 8 shows an exploded view of a lighting apparatus 800 according toanother implementation. The lighting apparatus includes alight-diffusive plate 802, first and second electrically conductivesheets 806 and 808, and an electrically insulative sheet 810 disposedbetween the first and second electrically conductive sheets. The firstand second electrically conductive sheets 806 and 808, which areillustrated with thicker line segments, may be aluminum or copper,depending on implementation requirements. Also, the thickness of theelectrically conductive sheets may vary, such as from foil to thickersheets. The evenness of current distribution and ability to dissipateheat by the electrically conductive sheets may vary according to thesurface area and thickness of the sheets.

The light-diffusive plate 802 has opposing first and second faces 820and 822 that are bounded by one or more sides. In the illustratedexample, the light-diffusive plate is rectangular and has four sides,with sides 812 and 814 exposed and sides 816 and 818 hidden in the view.The first face 820 is mostly obscured by the electrically conductivesheet 806, and the opposing second face 822 is hidden in the view. Thelight-diffusive plate may be transparent or translucent depending onimplementation requirements.

In one implementation, the light-diffusive plate is made from atransparent thermoplastic such as polymethyl methacrylate (PMMA or“acrylic glass”). The light-diffusive plate 802 may be any polygon or ashape bounded by one or more curved sides, such as a circle, ellipse, oran irregular shape.

The first electrically conductive sheet 806 is disposed on the firstface 820 of the light-diffusive plate 802 and may be attached to thelight-diffusive plate with adhesive between edge areas of theelectrically conductive sheet and the light-diffusive plate. Inalternative implementations, a frame (not shown) may hold together theelectrically conductive sheets 806 and 808, the insulative sheet 810,and the light-diffusive plate.

The electrically insulative sheet 810 is disposed on the firstelectrically conductive sheet 806 and insulates the first electricallyconductive sheet from the second electrically conductive sheet 808.Adhesive may be used to attach the electrically insulative sheet to thefirst electrically conductive sheet, and the second electricallyconductive sheet to the electrically insulative sheet. The electricallyconductive sheets 806 and 808 may include respective tabs 844 and 846for connecting to a power source.

The electrically conductive sheets 806 and 808 and the insulative sheet810 have respective sets of openings that are aligned. For example, oneof the openings in electrically conductive sheet 806 is opening 819,which is aligned with opening 821 in the electrically insulative sheet810 and with opening 823 in the electrically conductive sheet 808. Thealignment of the openings permits the SSL elements to be disposed in theopenings and connected to the electrically conductive sheets. Forexample, one of the SSL elements is SSL element 825, which is disposedwithin the openings 819, 821, and 823. The SSL elements are arrangedsuch that light-emitting portions of the SSL elements are directed atface 820 of the light-diffusive plate. The SSL elements 124 may bepackaged SSL elements or bare dice.

Each of the SSL elements has at least an anode and a cathode forconnecting to the electrically conductive sheets. In an exampleimplementation, the anodes and cathodes of the SSL elements are wirebonded to the electrically conductive sheets. For example, SSL element827 is connected to the electrically conductive sheet 806 with bond wire829 and connected to the electrically conductive sheet 808 with bondwire 831. Though not shown, a current control device, such as aresistor, may be coupled between one of the anode or cathode and theelectrically conductive sheets. In addition and though not shown, itwill be appreciated that the SSL elements may have control terminals.The control terminals may enable dimming, adjusting of color-tone, andturning-on and turning-off power to the SSL elements.

The pattern of the openings in the conductive and insulative sheets andthe arrangement of SSL elements may be varied according toimplementation requirements. For example, different implementations maycall for different sizes, numbers, and/or locations of the SSL elementson the light-diffusive plate 802.

The lighting apparatus 808 has anodes of the SSL elements connected tothe electrically conductive plate 806 and the cathodes of the SSLelements connected to the electrically conductive plate 808. It will beappreciated that in an alternative implementation, the cathodes of theSSL elements may be connected to the electrically conductive plate 806and the anodes of the SSL elements may be connected to the electricallyconductive plate 808.

FIG. 9 is a side, cross-sectional view of a portion of a back-litlighting apparatus similar to the lighting apparatus 800 of FIG. 8. SSLelements 902 is disposed in the aligned openings of the electricallyconductive sheets 806 and 808 and electrically insulative sheet 810. TheSSL elements is mechanically and electrically connected to theelectrically conductive sheets 806 and 808 by bond wires 904 and 906,respectively.

The openings in the electrically conductive sheet 808 and in theelectrically insulative sheet 810 are larger than the opening in theelectrically conductive sheet 806. The larger size openings in theelectrically conductive sheet 808 and in the electrically insulativesheet 810 permit the bond wire 904 to attach to the electricallyconductive sheet 806.

The SSL element is encapsulated in jettable material 908, such as asilicone. The encapsulation of the SSL element seals and protects thebond wires 904 and 906 and the connections from impacts and corrosivecontaminants.

FIG. 10 is a side, cross-sectional view of a portion of a back-litlighting apparatus similar to the lighting apparatus 800 of FIG. 8, withan additional electrically insulative layer and electrically conductivelayer. The additional electrically insulative layer 1002 andelectrically conductive layer 1004 may be used to provide a controlsignal to the SSL element 1006. The control signal may be for dimming,adjusting of color-tone, and turning-on and turning-off power to the SSLelements.

The openings in the electrically conductive sheet 1004 and in theelectrically insulative sheet 1002 are larger than the openings in theelectrically conductive sheet 808 and in the electrically insulativesheet 810, and the openings in the electrically conductive sheet 808 andin the electrically insulative sheet 810 are larger than the opening inthe electrically conductive sheet 806. The progressively larger openingspermit the bond wire 1008 to attach to the electrically conductive sheet806, bond wire 1010 to attach to the electrically conductive sheet 808,and bond wire 1012 to attach to electrically conductive sheet 1004. TheSSL element is encapsulated in jettable material 516.

FIG. 11 is a side, cross-sectional view of a portion of a back-litlighting apparatus similar to the lighting apparatus 800 of FIG. 8, withan additional control wire 1102. The additional control wire 1102 may beused to provide a control signal to the SSL element 1104. The controlsignal may be for dimming, adjusting of color-tone, and turning-on andturning-off power to the SSL elements.

In one implementation, the wire 1102 is an insulated wire and isdisposed on a surface of the electrically conductive sheet 808. The wiremay be attached to the electrically conductive sheet using a pressuresensitive adhesive, for example. The wire may be a fine gauge, round(round cross-section), bare wire. For example, 44 gauge (AWG) copperwire has been found to be suitable for some applications. However,different gauges may be suitable for different applications. “Wire” asused herein does not refer to printed or printed-and-etched patterns ofconductive material. Rather, as used herein wire refers to one or morestrands of conductive material that have been made by drawing theconductive material through draw plates, for example.

The connecting portions of the wire 1102 have planar landing areas towhich bond wires from the SSL elements s may be connected. The planarlanding areas extend longitudinally (lengthwise) along the wire. Theconnecting portions of the wire may be milled to form the planar landingareas on the wire. Alternatively, connecting portions of the wire may bestamped to form the planar landing areas and the insulation may bestripped from the portions of the wire to which the bond wires are toconnect, leaving insulation between the wire and the electricallyinsulative sheet 808. Bond wire 1106 connects the SSL element 1106 tothe planar landing area of the wire 1102. In an example implementation,the wire 1102 is copper, and the bond wire 1106 is either gold oraluminum. Aspects of wire bonding to a round wire are also described inthe co-pending U.S. patent application Ser. No. 14/553,519, entitled,“Wire Bonded IC Components to Round Wire,” filed on Nov. 25, 2014 byScott Lindblad et al., and is assigned to the same assignee as thepresent application, and the entire contents of the co-pending patentapplication Ser. No. 14/553,519 are incorporated herein by reference.The entire contents of co-pending patent application Ser. No.14/928,289, entitled, “Wire Bonded Electronic Devices to Round Wire,”filed on Oct. 30, 2015, by Robert Neuman, and is assigned to the sameassignee as the present application, are incorporated herein byreference.

The openings in the electrically conductive sheet 808 and in theelectrically insulative sheet 810 are larger than the opening in theelectrically conductive sheet 806. The progressively larger openingspermit the bond wire 1108 to attach to the electrically conductive sheet806 and bond wire 1110 to attach to the electrically conductive sheet808. The SSL element is encapsulated in jettable material 908.

FIG. 12 shows an enclosure 1200. The enclosure 1200 may be combined witheither the lighting apparatus 100 of FIG. 1 or the lighting apparatus800 of FIG. 8. The enclosure may be constructed with sheet metal andserve as both a heat sink for the SSL elements s in the lightingapparatus and as an enclosure to maintain the structural relationshipsbetween the light-diffusive plate, electrically conductive sheets, andelectrically insulative sheet(s) of the different lighting apparatusesas described above. The enclosure may be any type of metal suitable foran intended application.

The enclosure includes a back portion 1202 that is bounded by sides1204, 1206, 1208, and 1210. A lighting apparatus may be disposed withinthe recess of the enclosure formed by the sides 1204, 1206, 1208, and1210 such that the light-emitting face (e.g., face 122 in FIG. 1 andface 822 in FIG. 8) of the light-diffusive plate faces the open portionof the enclosure. Though not shown, it will be recognized that anadditional electrically insulative sheet may be disposed between theback portion 1202 and the electrically conductive sheet (108 of FIG. 1or 808 of FIG. 8) of the lighting apparatus. In an exampleimplementation, sides may have portions that are bent inward toward theopening of the enclosure to secure the lighting apparatus within theenclosure.

FIG. 13 shows a heat sink 1300. The heat sink 1300 may be combined witheither the lighting apparatus 100 of FIG. 1 or the lighting apparatus800 of FIG. 8 and may be constructed with sheet metal, which serves as aheat sink for the SSL elements in the lighting apparatus. The heat sinkincludes a back portion 1302 and a side 1304. A lighting apparatus maybe disposed against the heat sink such that the light-emitting face(e.g., face 122 in FIG. 1 and face 822 in FIG. 8) of the light-diffusiveplate faces away from the back portion 1302, and the SSL elements in theSSL element carrier 126 contact or nearly conact the side 1304. Thoughnot shown, it will be recognized that an additional electricallyinsulative sheet may be disposed between the back portion 1302 and theelectrically conductive sheet (108 of FIG. 1 or 808 of FIG. 8) of thelighting apparatus. For the lighting apparatus 800, the side 1304 may beunnecessary, and the heat sink may comprise only the back portion 1302,which is disposed against the SSL elements, such as SSL element 825 inFIG. 8. The heat sink may be any type of metal suitable for an intendedapplication.

Though aspects and features may in some cases be described in individualfigures, it will be appreciated that features from one figure can becombined with features of another figure even though the combination isnot explicitly shown or explicitly described as a combination.

The present invention is thought to be applicable to a variety oflighting applications. Other aspects and embodiments will be apparent tothose skilled in the art from consideration of the specification andpractice disclosed herein. It is intended that the disclosed apparatusand method be considered as examples only, with a true scope of theinvention being indicated by the following claims.

What is claimed is:
 1. A lighting apparatus, comprising: alight-diffusive plate having opposing first and second faces bounded byone or more sides; a first electrically conductive sheet disposed on thefirst face of the light-diffusive plate; a first electrically insulativesheet disposed on the first electrically conductive sheet; a secondelectrically conductive sheet disposed on the first electricallyinsulative sheet; and a first plurality of solid-state lighting (SSL)elements having light emitting portions that face a portion of thelight-diffusive plate, the first plurality of SSL elements electricallycoupled to the first electrically conductive sheet and to the secondelectrically conductive sheet; a first SSL element carrier attached tothe light-diffusive plate, wherein the first plurality of SSL elementsis disposed on a first portion of the SSL element carrier and the lightemitting portions of the SSL elements face a first side of the one ormore sides of the light-diffusive plate, and the first SSL elementcarrier has a second portion having first terminals and second terminalscoupled to the plurality of SSL elements; wherein: the light-diffusiveplate has a plurality of disruptions on the first face of the opposingfaces; the first electrically conductive sheet is electrically coupledto the first terminals; and the second electrically conductive sheet iselectrically coupled to the second terminals.
 2. The lighting apparatusof claim 1, wherein: the second portion of the first SSL element carrierhas first and second surfaces, the first surface of the second portionhaving the first terminals facing the first face of the light-diffusiveplate, and the second surface of the second portion facing away from thefirst face of the light diffusive plate and having the second terminals;the first electrically conductive sheet is directly electrically coupledto the first terminals; and the second electrically conductive sheet isdirectly electrically coupled to the second terminals.
 3. The lightingapparatus of claim 1, wherein the first electrically conductive sheet isone of an aluminum sheet or a copper sheet.
 4. The lighting apparatus ofclaim 3, wherein the second electrically conductive sheet is one of analuminum sheet or a copper sheet.
 5. The lighting apparatus of claim 1,wherein the first electrically conductive sheet is one of an aluminumfoil or a copper foil.
 6. The lighting apparatus of claim 5, wherein thesecond electrically conductive sheet is one of an aluminum foil or acopper foil.
 7. The lighting apparatus of claim 1, further comprising areflector disposed between the first face of the light-diffusive plateand a surface of the first electrically conductive sheet that faces thefirst face of the light-diffusive plate.
 8. The lighting apparatus ofclaim 1, wherein the first terminals are copper, the first electricallyconductive sheet is aluminum, and the first electrically conductivesheet is directly coupled to the first terminals with a weld joint. 9.The lighting apparatus of claim 8, wherein the second terminals arecopper, the second electrically conductive sheet is aluminum, and thesecond electrically conductive sheet is directly coupled to the secondterminals with a weld joint.
 10. The lighting apparatus of claim 1,further comprising: a second SSL element carrier attached to thelight-diffusive plate and having a second plurality of SSL elementsdisposed on a first portion and the second plurality of SSL elementsfacing a second side of the one or more sides of the light-diffusiveplate, the second SSL element carrier having a second portion havingthird terminals and fourth terminals; wherein: the first electricallyconductive sheet is coupled to the third terminals; and the secondelectrically conductive sheet is coupled to the fourth terminals. 11.The lighting apparatus of claim 1, wherein: the light-diffusive platehas a first channel along at least a portion of the first side of theone or more sides; and the first plurality of SSL elements on the firstportion of the first SSL element carrier are disposed within the firstchannel.
 12. The lighting apparatus of claim 11, further comprising anultra-violet (UV) curable encapsulant that fills the first channel. 13.The lighting apparatus of claim 1, wherein the first SSL element carrieris one of a lead frame, a rigid substrate, or a flexible substrate. 14.The lighting apparatus of claim 1, further comprising: a secondelectrically insulative sheet disposed on the second electricallyconductive sheet; and a metal sheet disposed on the second electricallyinsulative sheet and having a portion disposed against the first portionof the SSL element carrier.
 15. A lighting apparatus, comprising: alight-diffusive plate having opposing first and second faces bounded byone or more sides; a first electrically conductive sheet disposed on thefirst face of the light-diffusive plate; a first electrically insulativesheet disposed on the first electrically conductive sheet; a secondelectrically conductive sheet disposed on the first electricallyinsulative sheet; and a first plurality of solid-state lighting (SSL)elements having light emitting portions that face a portion of thelight-diffusive plate, the first plurality of SSL elements electricallycoupled to the first electrically conductive sheet and to the secondelectrically conductive sheet; wherein; the first electricallyconductive sheet has a first plurality of openings that are aligned witha second plurality of openings in the first electrically insulativesheet and a third plurality of openings in the second electricallyconductive sheet; and the first plurality of SSL elements are disposedin first plurality of openings, respectively, and the light emittingportions of the SSL elements face the first face of the light-diffusiveplate.
 16. The lighting apparatus of claim 15, wherein: the firstplurality of SSL elements are wire bonded to the to the firstelectrically conductive sheet and to the second electrically conductivesheet.
 17. The lighting apparatus of claim 16, wherein the first,second, and third pluralities of openings are filled with an encapsulentthat individually covers each of plurality of SSL elements and connectedbond wires.
 18. The lighting apparatus of claim 15, further comprising:a second electrically insulative sheet having a fourth plurality ofopenings aligned with the third plurality of openings of the secondelectrically conductive sheet and disposed on the second electricallyconductive sheet; a third electrically conductive sheet having a fifthplurality of openings aligned with the fourth plurality of openings ofthe second electrically insulative sheet and disposed on the secondelectrically insulative sheet; wherein the first plurality of SSLelements have control terminals coupled to the third electricallyconductive sheet.
 19. The lighting apparatus of claim 18, wherein: thefirst plurality of SSL elements are wire bonded to the to the firstelectrically conductive sheet, to the second electrically conductivesheet, and to the third electrically conductive sheet.
 20. The lightingapparatus of claim 15, further comprising: a control wire having anelectrically insulative jacket disposed on the second electricallyconductive sheet; wherein the first plurality of SSL elements havecontrol terminals coupled to the control wire.
 21. The lightingapparatus of claim 20, wherein: the first plurality of SSL elements arewire bonded to the to the first electrically conductive sheet, to thesecond electrically conductive sheet, and to the control wire.
 22. Thelighting apparatus of claim 20, wherein the first, second, and thirdpluralities of openings are filled with an encapsulent that individuallycovers each of plurality of SSL elements and connected bond wires. 23.The lighting apparatus of claim 15, further comprising a secondelectrically insulative sheet disposed on the second electricallyconductive sheet.
 24. A method of making a lighting apparatus,comprising: disposing a first electrically conductive sheet on a firstface of the light-diffusive plate, the light-diffusive plate havingopposing first and second faces bounded by one or more sides; connectinga plurality of solid-state lighting (SSL) elements to the firstelectrically conductive sheet with the plurality of SSL elementsarranged to emit light toward a portion of the light-diffusive plate;disposing an electrically insulative sheet on the first electricallyconductive sheet; disposing a second electrically conductive sheet onthe electrically insulative sheet; connecting the plurality of SSLelements to the second electrically conductive sheet; formingdisruptions on the first face of the light-diffusive plate; attachingthe plurality of SSL elements to a first portion an SSL element carrier,wherein the SSL element carrier includes first terminals and secondterminals coupled to the SSL elements; attaching the SSL element carrierto the light-diffusive plate, wherein the plurality of SSL elements arearranged to emit light toward a first side of the one or more sides ofthe light-diffusive plate, and the first terminals face the firstelectrically conductive sheet; connecting the first terminals to thefirst electrically conductive sheet; disposing an electricallyinsulative sheet on the first electrically conductive sheet, leaving thesecond terminals exposed; and disposing a second electrically conductivesheet on the electrically insulative sheet; and connecting the secondterminals to the second electrically conductive sheet.
 25. The method ofclaim 24, wherein the connecting the first terminals to the firstelectrically conductive sheet includes welding the first terminals tothe first electrically conductive sheet.
 26. The method of claim 25,wherein the connecting the second terminals to the second electricallyconductive sheet includes welding the second terminals to the secondelectrically conductive sheet.
 27. The method of claim 24, wherein thedisposing of the first electrically conductive sheet on the first faceof the light-diffusive plate includes disposing one of an aluminum sheetor a copper sheet on the first face of the light-diffusive plate. 28.The method of claim 27, wherein the disposing of the second electricallyconductive sheet on the electrically insulative sheet includes disposingone of an aluminum sheet or a copper sheet on the electricallyinsulative sheet.
 29. The method of claim 24, wherein the disposing ofthe first electrically conductive sheet on the first face of thelight-diffusive plate includes disposing one of an aluminum foil or acopper foil on the first face of the light-diffusive plate.
 30. Themethod of claim 29, wherein the disposing of the second electricallyconductive sheet on the electrically insulative sheet includes disposingone of an aluminum foil or a copper foil on the electrically insulativesheet.
 31. The method of claim 24, wherein the first terminals arecopper, the first electrically conductive sheet is aluminum, and theconnecting the first terminals to the first electrically conductivesheet includes welding the first terminals to the first electricallyconductive sheet.
 32. The method of claim 31, wherein the secondterminals are copper, the second electrically conductive sheet isaluminum, and the connecting the second terminals to the secondelectrically conductive sheet includes welding the second terminals tothe second electrically conductive sheet.
 33. The method of claim 24,further comprising: forming a first channel along at least a portion ofthe first side of the one or more sides of the light-diffusive plate;and wherein the attaching of the SSL element carrier to thelight-diffusive plate includes disposing the plurality of SSL elementswithin the first channel.
 34. The method of claim 33, furthercomprising: filling the first channel with an ultra-violet (UV) curableencapsulant; and curing the encapsulant in the first channel.
 35. Amethod of making a lighting apparatus, comprising: disposing a firstelectrically conductive sheet on a first face of the light-diffusiveplate, the light-diffusive plate having opposing first and second facesbounded by one or more sides; connecting a plurality of solid-statelighting (SSL) elements to the first electrically conductive sheet withthe plurality of SSL elements arranged to emit light toward a portion ofthe light-diffusive plate; disposing an electrically insulative sheet onthe first electrically conductive sheet; disposing a second electricallyconductive sheet on the electrically insulative sheet; connecting theplurality of SSL elements to the second electrically conductive sheet;wherein the first electrically conductive sheet has a first plurality ofopenings aligned with a second plurality of openings in the firstelectrically insulative sheet and a third plurality of openings in thesecond electrically conductive sheet; and disposing the plurality of SSLelements in the first, second, and third plurality of openings, with thelight emitting portions of the SSL elements facing the first face of thelight-diffusive plate.
 36. The method of claim 35, further comprisingwire bonding the plurality of SSL elements to the first electricallyconductive sheet and to the second electrically conductive sheet withbond wires.
 37. The lighting apparatus of claim 36, further comprisingindividually encapsulating each SSL element of the plurality of SSLelements, wherein the first, second, and third pluralities of openingsare filled with an encapsulent that individually covers each ofplurality of SSL elements and connected bond wires.
 38. The method ofclaim 35, further comprising: disposing a second electrically insulativesheet on the second electrically conductive sheet, the secondelectrically insulative sheet having a fourth plurality of openingsaligned with the third plurality of openings of the second electricallyconductive sheet; disposing a third electrically conductive sheet on thesecond electrically insulative sheet, the third electrically conductivesheet having a fifth plurality of openings aligned with the fourthplurality of openings of the second electrically insulative sheet;wherein the first plurality of SSL elements have control terminalscoupled to the third electrically conductive sheet.
 39. The method ofclaim 38, further comprising wire bonding the first plurality of SSLelements to the first electrically conductive sheet, to the secondelectrically conductive sheet, and to the third electrically conductivesheet.
 40. The method of claim 35, further comprising: attaching acontrol wire having an electrically insulative jacket to the secondelectrically conductive sheet; and connecting control terminals of thefirst plurality of SSL elements to the control wire.
 41. The method ofclaim 40, further comprising wire bonding the first plurality of SSLelements to the first electrically conductive sheet, to the secondelectrically conductive sheet, and to the control wire.